1. Field of the Invention
Embodiments of the present invention relate to the fabrication of integrated circuits. More particularly, embodiments of the present invention relate to a process for patterning and etching features in a semiconductor substrate.
2. Description of the Related Art
Integrated circuit geometries have dramatically decreased in size since such devices were first introduced several decades ago. Since then, integrated circuits have generally followed the two year/half-size rule (often called Moore's Law), which means that the number of devices on a chip doubles every two years. Today's fabrication facilities are routinely producing devices having 0.13 μm and even 0.1 μm feature sizes, and tomorrow's facilities soon will be producing devices having even smaller feature sizes.
The continued reduction in device geometries has generated a demand for methods of forming nanometer scale features that are separated by nanometer scale distances on semiconductor substrates. As the limits of optical resolution are being approached in current lithography processes, one method that has been developed to reduce the distance between features or devices on a substrate includes a double patterning of a hardmask layer that is used to transfer a pattern into the substrate. In the double patterning method, a hardmask layer is deposited on a substrate layer that is to be etched. The hardmask layer is patterned by a photoresist deposited on the hardmask layer. The photoresist is then removed, and a second pattern is introduced into the hardmask layer with a second photoresist that is deposited on the hardmask layer.
While current double patterning methods can be used to reduce the distance between features on a substrate, there remains a need for materials that can be used as hardmasks for double patterning methods. In particular, there is a need for double patterning hardmask layers that act as anti-reflective coatings that minimize reflections that can damage resolution during lithography. FIG. 1 (prior art) shows an example of a substrate 10 having features 12, 14 that were patterned at a low resolution. There is also a need for double patterning hardmask layers that have a good etch selectivity to the underlying substrate that is to be etched and are easily removable after the substrate is etched.